    .equ STACK_TOP, 0x20000800
    .text
    .global _start
    .code   16
    .syntax unified
_start:
    .word STACK_TOP, start
    .type start, function
start:
    movs    r0,     #10
    movs    r1,     #0
    /* 计算10+9+8+...1 */
loop:
    adds    r1,     r0
    subs    r0,     #1
    bne     loop
    /* 结果存在R1中 */
    ldr     r0,     =result
    str     r1,     [r0]
deadloop:
    b       deadloop
    /* 数据区 */
    .data
result:
    .word   0
    .end
